Paper
RSC Advances
2 2
Table 4 Comparison of the activity of various catalysts in the oxidation of benzyl methyl sulfide using H O
Entry
Catalyst
Conditions
Time (min)
Yield (%)
Ref.
1
2
3
4
5
6
7
8
9
MNPs–PA
SSA
NBS
Solvent-free, rt
10
40
15
20 h
150
330
240
360
180
40
95
96
90
52
96
92
83
53
83
92
100
99
24
37
36
33
34
31
32
35
CH
CH
CH
3
3
3
CN, rt
CN, 35–40 C
CN, 20 C
ꢀ
ꢀ
ꢀ
Cu(II) complex, TEMPO
TaCl
Cp/Mo(CO)
Silica-based ammonium tungstate
ZnBr , pyridine-2-3-carboxylic acid
Schiff base/Cu(II) salen/Fe
Co@SiO @[Mn(III)SBC]
Au/CTN-silica
Co@SiO [(EtO)
5
MeOH, 45 C
3
Cl
CH
CH
3
COCH
Cl :MeOH, rt
2
3
–MeOH
2
2
MeOH, rt
EtOH, 60 C
ꢀ
3
O
4
23
24
22
ꢀ
10
11
12
2
Solvent-free, 45 C
ꢀ
60 C
120
50
3
ꢀ
2
3
Si–L ]/Mn(III)
55 C
This work
4
M. J. Jacinto, H. C. F. Santos, R. F. Jardim, R. Landers and
L. M. Rossi, Appl. Catal., A, 2009, 360, 177.
Conclusion
3
In this study, the catalysts Co@SiO
2
[(EtO)
3
Si–L ]/Mn(III) and
5 R. L. Oliveira, P. K. Kiyohara and L. M. Rossi, Green Chem.,
2010, 12, 144.
6 L. Canali and D. C. Sherrington, Chem. Soc. Rev., 1999, 28, 85.
7 T. Katsuki, Coord. Chem. Rev., 1995, 140, 189.
8 R. Skoda-Foldes, L. Koll Jr and A. Arcadi, J. Mol. Catal., 1995,
101, 37.
3
Co@SiO [(EtO) Si–L ]/Co(II) were successfully prepared via
2 3
3
immobilizing the Schiff base ligand [(EtO) Si–L H] on the Co
3
nanoparticles coated with SiO2 and then reacting them with
metal salts viz. Mn(III) and Co(II). These catalysts were employed
for the oxidation of the suldes to sulfoxides and showed high
catalytic activity and selectivity. It was further found that the
9 B. S. Lane and K. Burgess, Chem. Rev., 2003, 103, 2457.
catalyst can be easily isolated using an external magnet and 10 G. Righi and C. Bonini, Synthesis, 1994, 3, 225.
reused seven times without signicant catalytic deactivation.
11 G. X. Zheng, J. J. Eisch, Z. R. Lui and X. Ma, J. Org. Chem.,
1992, 57, 5140.
These newly developed heterogeneous catalysts were simple
to prepare. These catalysts were found to be easily reusable 12 L. P. C. Nielson, C. P. Stevenson, D. G. Backmond and
several times aer reaction with an external magnet and drying
E. N. Jacobsen, J. Am. Chem. Soc., 2004, 126, 1360.
without signicant catalytic deactivation, which typically occurs 13 J. Lopez, S. Liang and X. R. Bu, Tetrahedron Lett., 1998, 39,
due to the leaching of the active species or degradation of the
4199.
structure. It appears that the Schiff base complex has played an 14 A. M. Daly, C. T. Dalton, M. F. Renehan and D. G. Gilheany,
important role in the stabilization of metal catalyst particles.
Tetrahedron Lett., 1999, 40, 3617.
These unique results open new perspectives for the application 15 H. Keypour, S. G. Saremi, H. Veisi and R. Azadbakht, RSC
of these types of magnetic catalysts in other organic reactions.
Adv., 2016, 6, 77020.
16 M. Szavuly, S. D. Szilvasi, R. Csonka, D. Klesitz, G. Speier,
M. Giorgi and J. Kaizer, J. Mol. Catal. A: Chem., 2014, 393,
Conflicts of interest
3
17.
17 S. Rayati, F. Nejabat and S. Zakavi, Inorg. Chem. Commun.,
014, 40, 82.
There are no conicts to declare.
2
1
8 P. Gogoi, M. Kalita, T. Bhattacharjee and P. Barman,
Tetrahedron Lett., 2014, 55, 1028.
Acknowledgements
1
2
9 X. T. Zhou and H. B. Ji, Catal. Commun., 2014, 53, 29.
0 B. Yu, C. X. Guo, C. L. Zhong, Z. F. Diao and L. N. He,
Tetrahedron Lett., 2014, 55, 1818.
1 Y. Imada, T. Kitagawa, S. Iwata, N. Komiya and T. Naota,
Tetrahedron, 2014, 70, 495.
We thank the Payame Noor University, Bu-Ali Sina University
and Center for Research and Development of Petroleum Tech-
nologies at Kermanshah, Research Institute of Petroleum
Industry (RIPI), Iran for their partial support on this project.
2
2
2
2
2
2 A. R. Judy Azar, E. Safaei and S. Mohebbi, Mater. Res. Bull.,
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RSC Adv., 2018, 8, 3889–3898 | 3897